Actor Gary Oldman has revealed he suffered an unexpected and painful baptism in the leafy surroundings of Hampstead Ponds.

The 53-year-old stars in the latest film adaptation of John le Carr�’s spy novel Tinker Tailor Soldier Spy, in what is being tipped as an Oscar-winning performance.

It is set in 1970s London and Oldman plays the role of George Smiley - a studious and principled English spy cast out of the service in a reshuffle who takes regular swims in Hampstead Ponds to fill the void left by his sacking.

But the experience came as something of a shock for the Hollywood star as he filmed on location.

Oldman said: “It was deathly cold, but I couldn’t complain because there were these 80-year-old geezers swimming beside me.

“I couldn’t say ‘God, I’m cold’. It actually took me a whole day to warm up. I will never forget Hampstead Ponds.”

Swedish director Tomas Alfredson revealed the film crew thought they might have lost Oldman at one point - with his thoughts turning to the legal case that might follow.

But he congratulated Oldman on the scenes and said: “You were very brave and you didn’t complain once.”

They spoke last Friday (September 16) at a screening at Everyman Cinema in Belsize Park - an area that was also used in the filming of Tinker Tailor Soldier Spy.

Director Alfredson said he was “breast fed” on English television growing up and chose Hampstead and Belsize Park for filming because it helped him realise an authentic 1970s feel.

Oldman said: “Tomas calls it the foreskin - it’s that orange colour, to capture that brown orange smokey shade.”

Everyman group chairman Paul Wise was in his Belsize Crescent office when a 100-strong film crew pitched up outside.

He said: “Everyone was there and it was extremely exciting.

Film crews by their very nature are exciting to see and to see a film like this behind the scenes was something else.”

Asked whether there was a sequel in the offing, Oldman said he would only consider it if he was working with the same team.

And, presumably, if there is no mention of a leisurely dip in Hampstead Ponds lurking somewhere in the script.